The Army's Redstone and Jupiter Vehicles
 The Army's principal missile team was formed around 120 German rocket experts brought to the United States in 1945. First stationed at Fort Bliss, Texas, the Germans were transferred to the Army's Redstone Arsenal, Huntsville, Alabama, in 1950; and they were soon deeply involved in the Army's growing missile development program. The technical group was headed by Wernher von Braun, who had held the same position at Peenemijnde during the development of the German A-4 (V-2) rocket, the beginning of modern rocketry.4
 The first large Army ballistic missile was the Redstone, modeled after the V-2. Redstone was powered by a North American Aviation rocket engine developing 334 kilonewtons (75 000 lb thrust) using an alcohol-water mixture and liquid oxygen. During eight years of research and development and 37 flights, the Redstone evolved into a 322-kilometer-range vehicle, 21 meters tall, 1.8 meters in diameter, weighing 27 670 kilograms at launch.5
A space enthusiast since youth, von Braun proposed a satellite launch vehicle based on Redstone in 1954, a year after the first Redstone launch. In 1955, his team submitted a proposal for a satellite launch vehicle to the Department of Defense. Called Jupiter C, it consisted of a modified Redstone with two solid-propellant upper stages. This design was used in a joint Army-Navy proposal to the Stewart committee, but it was not selected. Disappointed, von Braun soon found another application-study of aerodynamic heating of a warhead reentering the atmosphere during a ballistic trajectory. Three Jupiter Cs were launched, the last less than two months before Sputnik I. After this flight, the commander of the Army Ballistic Missile Agency (ABMA) at Redstone Arsenal, Maj. Gen. John Bruce Medaris, ordered the remaining Jupiter equipment into storage. As enthusiastic a space proponent as von Braun, Medaris was waiting for the right opportunity to show what ABMA could do in spaceflight.6
The perfect opportunity soon came. Medaris and von Braun were dinner hosts to visiting Neil McElroy, who was succeeding Charles Wilson as Secretary of Defense, when word came that Sputnik I was launched. The rest of the evening and the following morning were devoted to what ABMA could do. On 31 January 1958, the Medaris-von Braun team launched Explorer I, first American satellite, using a modified Jupiter C vehicle.*
* It consisted of a modified Redstone first stage and three upper stages of solid rockets. The three upper stages used 11.6, and 1 Sergeant solid rockets, respectively. The Sergeant, 11 cm in diameter, was developed by the Jet Propulsion Laboratory, which teamed up with ABMA in building and launching the first satellite.